A Cytological and Cytochemical Investigation of the Development of T H E Viral Papilloma of Human Skin*, By

Some types of verrucae of human skin have long been known to be caused by a filterable infectious agent (1), and as such, represent the only kind of tumorous growth in man definitely known to be virus-induced. Warts of this kind, characterized cytologically by intranuclear inclusion bodies and cytoplasmic masses (2--4) have been shown to yield crystalline viral particles (5). The cytology and histochemistry of these skin papillomas have been studied, in some aspect, by several investigators (3, 4, 6, 7). Bunting eta/. (4) dearly distinguished the cells of this group of papillomas from those of other more common types of wart by the presence of eosinophilic intranuclear inclusion bodies, and failure of infected cells to differentiate normally. Observations with the electron microscope have disclosed viral particles in the cells of the papilloma (8). Further study by Bunting (9), the results of which are detailed in this communication, have revealed a succession of steps in the evolution of the pathological changes in affected cells, which are accompanied by marked tinctorial and histochemical alterations. Since the stages could be readily identified, it seemed desirable to determine the deoxyribonucleic acid (DNA) content of the cells cytochemically at each recognizable step in the progress of the infection. From studies of the relative nucleic acid content per cell it was hoped to gain information on the synthesis of DNA in infected cells in relation to viral development, and on the nature of other cell forms to be described that occur in the lesion.